A variety of optical communications modules are used in optical networks for transmitting and receiving optical data signals over the networks. An optical communications module may be an optical receiver module that has optical receiving capability, but not optical transmitting capability. Alternatively, an optical communications module may be an optical transmitter module that has optical transmitting capability, but not optical receiving capability. Alternatively, an optical communications module may be an optical transceiver module that has both optical transmitting and optical receiving capability.
A typical optical transmitter or transceiver module has a transmitter optical subassembly (TOSA) that includes a laser driver circuit, at least one laser diode and various other electrical components. The laser driver circuit outputs an electrical drive signal to each respective laser diode to cause the respective laser diode to be modulated. When the laser diode is modulated, it outputs optical signals that have power levels corresponding to logic 1s and logic 0s. An optics system of the module focuses the optical signals produced by each respective laser diode into the end of a respective transmit optical fiber held within an optical connector module that connects to the optical transmitter or transceiver module.
A typical optical receiver or transceiver module has a receiver optical subassembly (ROSA) that includes at least one receive photodiode and various other electrical components. An optics system of the ROSA focuses an optical data signal that is output from the end of an optical fiber onto a photodiode of the ROSA. The photodiode converts the incoming optical data signal into an electrical analog signal. An electrical detection circuit, such as a transimpedance amplifier (TIA), receives the electrical signal produced by the photodiode and outputs a corresponding amplified electrical signal, which is processed by other circuitry of the ROSA to recover the data.
Many different types of optical communications modules are available in the market, including single-channel optical transmitter and receiver modules, dual-channel optical transceiver modules, and parallel optical transmitter, receiver and transceiver modules. Many different types of optics systems are used in these optical communications modules. The optics systems perform the functions of collimating laser light into a collimated beam and directing the collimated beam, or portions thereof, in one or more directions. Typical optics systems include one or more refractive, diffractive, holographic, and/or reflective optics for performing these functions.
One of the difficulties associated with many optics systems that are currently used in optical communications modules is that they must be manufactured with very high precision, which can lead to high manufacturing costs. Another difficulty associated with many optics systems is that the relative positioning of the components of the optics system and the optoelectronic device (e.g., the laser diode or photodiode) must be very precise in order to avoid unacceptable optical losses and to ensure high signal integrity. Because of the need for very precise positioning of these components, the processes of aligning the components and securing them in position can be difficult and time consuming, which can also lead to higher costs.
A need exists for an optics system that can be manufactured with very high precision at relatively low cost and that facilitates the process of precisely positioning the optoelectronic devices and the optics system relative to one another inside of the modules.